Photographic materials that have been widely popularized in these days are such that silver halide emulsions were dispersed in a water-soluble colloid such as gelatin and the dispersions were coated on a support while they were crosslinked (hardened) with a crosslinking agent (hardening agent) so as not to dissolve out in processing solutions during development. In addition to these, various additives were added to photographic materials so as to ensure various photographic properties for them. Of these additives, hardly water-soluble photographically useful reagents (for example, oil-soluble couplers, antioxidants to be used for preventing fading, color-fogging and color-mixing (such as alkylhydroquinones, alkylphenols, chromans, coumarones, etc.), hardening agents, oil-soluble filter dyes, oil-soluble ultraviolet absorbents, oil-soluble brightening agents, DIR compounds (such as DIR hydroquinones, non-coloring DIR couplers, etc.), developing agents, color-developing agents, DDR redox compounds, DDR couplers) are first dissolved in a suitable oil-forming reagent or a high boiling point solvent, then the solutions are dispersed in a solution of a hydrophilic colloid, especially gelatin, in the presence of a surfactant, and the resulting dispersions are added to hydrophilic organic colloid layers (for example, light-sensitive emulsion layers, filter layers, backing layers, anti-halation layers, interlayers, protective layers). As high boiling point organic solvents, generally used are phthalate compounds and phosphate compounds.
Phthalate compounds and phosphate compounds which are high boiling point organic solvents have heretofore been much employed in this technical field, as being excellent in that they have high ability of dispersing couplers, high affinity for colloids such as gelatin, high ability of stabilizing color images formed and little influence on the hue of color images formed and that they are chemically stable in photographic materials and are available at low costs.
High boiling point organic solvents to be used in preparing recent photographic materials are needed to meet various requirements.
On the other hand, recently, there is a great need of having photographic prints seen immediately after photographing and a great need of minimizing the amounts of waste from photographic processing. In order to meet these needs, means for rapid photographic processing and means for LR (lowering replenishers) are being advanced greatly. However, such rapid photographic processing and LR involve various problems. For example, the processed photographic materials are much stained, the stability during development is impaired, the stability of images formed is impaired during storage, the graininess of processed photographic materials is decreased, the hue of color images formed is turbid, and the processed photographic materials are to be much stained after storage. It is an important theme to solve these problems in improving photographic materials these days.
In addition, photographic materials have become worked into various forms in these days, after being developed. For example, the surfaces of developed photographic materials are matted or textured by spraying or using surface-modifying rollers, or the developed photographic materials are laminated by sandwiching them with plastic films, are colored with special painting materials, or are decolored or bleached with various bleaching agents. It is understood that the aptitudes for such treatments greatly vary, depending on the planning of photographic materials. For example, some coloring materials were unfavorably discolored when sprayed with matting agents or when laminated, or were hardly bleached with bleaching agents, or were hardly painted with painting materials. Therefore, the post-processing treatment suitability of developed photographic materials was an extremely important matter for photographic materials.